1. Field of the Invention
The present invention relates to a substrate processing apparatus for applying a processing solution such as a resist solution or the like to the front face of a substrate to be processed such as a semiconductor wafer or the like.
2. Description of the Related Art
In the process of fabricating semiconductor devices (IC chips) and LCDs, a fine pattern is formed on the front face of a substrate to be processed such as a semiconductor or a glass substrate with high precision and high density by means of photolithography.
In the fabrication of semiconductor devices, for example, after a resist solution is applied on the front face of the semiconductor wafer, the semiconductor wafer is exposed in accordance with a predetermined pattern, and then subjected to developing processing and etching processing, whereby a predetermined circuit pattern is formed.
In recent years, the line width of a semiconductor circuit to be formed by photolithography has tended to become finer, and with this tendency, it is stringently required to make a resist film thinner and to make film thickness uniform. Namely, it is desirable to make the thickness of a resist solution film thin and uniform as much as possible since the line width of a circuit to be formed is proportional to the thickness of the resist solution film and the wavelength of exposure.
In a spin-coating method, the thickness of a resist film can be controlled by regulating the rotation speed of the wafer. Therefore, in the case of the wafer 300 mm in diameter, it is possible to make a film thinner by rotating the wafer at a considerably higher speed.
Since the wafer is rotated at a high speed in this spin-coating method, the amount of a resist solution thrown out to the outside of the wafer from the edge portion of the wafer is large. In the spin-coating method, the wafer is rotated in a cup in order to catch the resist solution thrown out.
Moreover, in this case, air is exhausted from the bottom of the cup in order to prevent the resist solution thrown out of the edge portion of the wafer to fly high above the cup in the form of mist and contaminate other apparatus. Thereby, a down flow in a clean room is drawn in from the upper side of the cup, and an air flow from the upper side to the lower side is formed in the cup, thus preventing mist of the resist solution to fly off to the upper side of the cup.
In the case of a resist coating apparatus in which a wafer is rotated at a high speed as described above, however, a phenomenon in which only a resist film at a peripheral edge portion of the wafer becomes thicker compared with that at the other portions (a phenomenon of an increase in film thickness at the peripheral edge portion) sometimes occurs.
An object of the present invention is to provide a substrate processing apparatus capable of preventing an increase in the thickness of a coating film at an outer edge portion of a substrate to be processed in the process of making the film thinner by spreading a coating film applied on the substrate to be processed by centrifugal force.
According to a first aspect of the present invention, a substrate processing apparatus, comprising: a substrate holding mechanism for holding a substrate to be processed to the front face of which a processing solution is supplied; a container for housing the substrate holding mechanism and forcibly exhausting an atmosphere around the substrate to be processed by exhaust from the bottom thereof; and an air flow control plate, provided in the container to surround the outer periphery of the substrate to be processed, for controlling an air flow in the vicinity of the substrate to be processed, is provided.
According to a second aspect of the present invention, a substrate processing apparatus for processing a substrate having a first face and a second face, comprising: a holding and rotating section for holding and rotating the first face of the substrate; a solution supplying section for supplying a solution to the second face of the substrate; and an air flow control plate, disposed to surround the outer periphery of the substrate being held and rotated, having a third face with almost the same height as the second face, the third face being provided with a through-hole, is provided.
According to a third aspect of the present invention, a substrate processing apparatus for processing a substrate having a first face and a second face, comprising: a holding and rotating section for holding and rotating the first face of the substrate; a solution supplying section for supplying a solution to the second face of the substrate; and a gas-liquid separating plate, disposed to surround the outer periphery of the substrate being held and rotated, allowing a gas flowing outward from the outer periphery of the substrate to pass over the second face and allowing a liquid flowing outward from the outer periphery of the substrate to pass over the first face.
These objects and still other objects and advantages of the present invention will become apparent upon reading the following specification when taken in conjunction with the accompanying drawings.